import matplotlib.pyplot as plt
import numpy as np
from scipy import signal

num = np.array([1, 2])
den = np.array([1, 4, 13])
z, p, k = signal.tf2zpk(num, den)

plt.plot(np.real(z), np.imag(z), "o", np.real(p), np.imag(p), "x")
plt.show()
